<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            position: relative;
            width: 400px;
            border-bottom: 1px solid #ccc;
            margin: 100px auto;
        }

        .box input {
            width: 370px;
            height: 30px;
            border: 0;
            outline: none;
        }

        .box img {
            position: absolute;
            top: 2px;
            right: 2px;
            width: 24px;
        }
    </style>
</head>
<body>
    <div class="box">
        <label for="">
            <img src="../images/close.png" alt="" id="eye">
        </label>
        <input type="password" name="" id="pwd">
    </div>
    <script>
        // 需求:点击图片，图片 src 变化，表单类型变化。
        let img = document.querySelector('img');
        let input = document.querySelector('input');

        let flag = true;
        img.onclick = function () {
            if (flag) {
                img.src = "../images/open.png";
                input.type = "text";
            } else {
                img.src = "../images/close.png";
                input.type = "password";
            }
            flag = !flag;
        }
    </script>
</body>
</html>